Dynamic regulation of LFA-1 activation and neutrophil arrest on intercellular adhesion molecule 1 (ICAM-1) in shear flow

J Biol Chem. 2002 Jun 7;277(23):20660-70. doi: 10.1074/jbc.M202223200. Epub 2002 Apr 2.

Abstract

Neutrophil recruitment during acute inflammation is triggered by G-protein-linked chemotactic receptors that in turn activate beta(2) integrin (CD18), deemed a critical step in facilitating cell capture and arrest under the shear force of blood flow. A conformational switch in the I domain allosteric site (IDAS) and in CD18 regulates LFA-1 affinity for endothelial ligands including intercellular adhesion molecule 1 (ICAM-1). We examined the dynamics of CD18 activation in terms of the efficiency of neutrophil capture of ICAM-1, and we correlated this with the membrane topography of 327C, an antibody that recognizes the active conformation of CD18 I-like domain. Adhesion increased in direct proportion to chemotactic stimulus rising 7-fold over a log range of interleukin-8 (IL-8). A threshold dose of approximately 75 pm IL-8, corresponding to ligation of only approximately 10-100 receptors, was sufficient to activate approximately 20,000 CD18 and a rapid boost in the capture efficiency on ICAM-1. This was accompanied by a rapid redistribution of active LFA-1, but not Mac-1, into membrane patches, a necessary component for optimum adhesion efficiency. Shear-resistant arrest on a monolayer of ICAM-1 was reversed within minutes of chemotactic stimulation correlating with a shift from high to low affinity CD18 and dispersal of patches of active CD18. Mobility of active CD18 into high avidity patches was dependent on phosphatidylinositol 3-kinase activity and not F-actin polymerization. The data reveal that the number of chemotactic receptors bound and the topography and lifetime of high affinity LFA-1 tightly regulate the efficiency of neutrophil capture on ICAM-1.

MeSH terms

  • Adult
  • Allosteric Regulation
  • Antibodies, Monoclonal / immunology
  • CD18 Antigens / immunology
  • Calcium / metabolism
  • Chemotaxis, Leukocyte
  • Fluorescent Antibody Technique
  • Humans
  • Intercellular Adhesion Molecule-1 / metabolism*
  • Interleukin-8 / pharmacology
  • Ion Transport
  • Kinetics
  • Lymphocyte Function-Associated Antigen-1 / metabolism*
  • Neutrophil Activation / drug effects
  • Neutrophils / cytology*
  • Neutrophils / drug effects

Substances

  • Antibodies, Monoclonal
  • CD18 Antigens
  • Interleukin-8
  • Lymphocyte Function-Associated Antigen-1
  • Intercellular Adhesion Molecule-1
  • Calcium